5.12 understand how restriction enzymes are used to cut DNA at specific sites and ligase enzymes are used to join pieces of DNA together

Restriction enzyme: an enzyme that recognizes specific sequences of DNA and cut the DNA at these points to obtain desired genes

Ligase enzyme: uses to join two pieces of DNA together by forming bonds between vector and genes.

Recombinant DNA: two different bits of DNA stuck together

Vector: something that is used to transfer DNA into a cell. There are two types of vectors: plasmids and viruses. Plasmids are small, circular molecules of DNA that can be transferred between bacteria. Viruses insert DNA into the organisms they infect.

Method: 

1. A restriction enzyme is used to recognize a certain base sequence in a DNA strand, and the DNA is cut out using the same restriction enzyme. The cut can be straight with blunt ends, but most of the time the restriction enzyme cuts the DNA with staggered cuts to leave "sticky ends". Sticky ends allow fragments of DNA and vector DNA to overlap ends with complementary bases.

2. The vector DNA and the DNA you're inserting are mixed together with ligase enzymes. 

3. The ligase enzymes form bonds between vector and gene to join them together to produce recombinant DNA.

4. The recombinant DNA is inserted into other cells such as bacteria/viruses.

5. These cells can now use the gene you inserted to make the protein you want. For example, bacteria containing the gene for human insulin can be grown in large numbers in a fermenter to produce insulin for people with diabetes.